Vocal Exercises

Vocal exercises are done by every choir and vocal student across the world. They are most beneficial prior to singing but can be used at anytime. I traditionally use lip trills, 5 note scales and arpeggios with a series of syllables (ex. na-nee-na-nee-na). What exercises have you used in the past that you have enjoyed? What about them did you like? Try to explain the benefit of using that particular vocal exercise.